As drink ingredients, cordials are just as important as the base liquors in the bar. If vodka, gin, whiskey, and the like are the rock stars of the cocktail, then liqueurs are the backup singers.
Cordials are made with a base liquor. It can be anything from neutral grain alcohol to brandy, whiskey, or rum. Sugar is often added along with a mix of herbs, fruits, spices, and other ingredients to obtain the desired flavour. Several liqueurs use artificial flavours and colours; this is particularly true among the cheaper brands.